Method of treating tobacco



United States Patent 3,327,716 METHOD OF TREATING TOBACCO Leonard Raymond Kohan, Yonkers, N.Y., and Donald Allen Kaul, Silver Spring, Md, assignors to American Can Company, New York, N.Y., a corporation of New York No Drawing. Filed July 24, 1964, Ser. No. 385,041 8 Claims. (Cl. 131-120) This invention relates to a method of treating tobacco and more particularly to a method of heat treating tobacco to remove undesirable ingredients therefrom.

There has been increasing concern in recent times about the harmful elfects of cigarette smoking on the health of smokers. In particular, there have been a great many studies and theories which have advanced the proposition that cigarette smoking and carcinoma are somehow inter-related. While no one has been able to precisely analyze the manner in which cigarettes create carcinogenic effects in human beings, it has at least been theorized that the tobacco itself contains certain carcinogenic agents or materials which are transmitted to the smoker as the tobacco burns.

It has been known for some time that ionizing radiation exhibits carcinogenic effects in man. Therefore, it was theorized that perhaps the cigarette tobacco contained such a radioactive substance and that this substance was at least partially responsible for the carcinoma which often occurred in cigarette smokers. Studies directed toward such a theory established that cigarette tobacco did, in fact, contain such a substance as a natural constituent. The substance discovered was polonium 210, and it was concluded that the radiation dosage from the alpha particles emitted from polonium 210 could be a significant factor in inducing bronchial cancer in smokers.

Recently, scientific tests have discovered how polonium 210 reacts with cigarette tobacco as it is burned during smoking. Since polonium 210 is completely volatile above 500 C., it readily vaporizes during the normal smoking of a cigarette as the average cigarette reaches a peak temperature of 880 :35" C. when puffed by the average smoker.

Since polonium attaches itself readily and strongly to surfaces, it is thought that it is readily bondable to smoke particles which are inhaled while smoking a cigarette. Because polonium 210 emits alpha particles and has an intermediate halflife of 138 days, there is suflicient time for the alpha particles to have an effect upon the bronchial system of the smoker before the particles completely decay.

It is therefore an object of the present invention to provide a method of removing undesirable ingredients from tobacco which is to be used in smoking.

Another object of this invention is to provide a method of removing undesirable ingredients from tobacco by heat treating the tobacco.

A further object is to provide a method of removing a natural ingredient, polonium 210, from tobacco without necessarily damaging the flavor of the tobacco.

Yet another object is to provide a method of vaporizing volatile polonium 210 from tobacco without combustion of the tobacco.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which discloses a preferred embodiment thereof.

The above objects are accomplished by placing a quantity of tobacco in a suitable closed heating chamber and establishing non-oxidizing conditions within the chamber. Thereafter the tobacco is heated in the non-oxidizing conditions to a temperature above 500 C., but below the combustion temperature of the tobacco in the non-oxi- 3,327,716 Patented June 27, 1967 dizing conditions, thereby vaporizing and separating undesirable ingredients from the tobacco.

As a preferred or exemplary embodiment of the instant invention a quantity of tobacco, preferablyin a slitted or shredded form, is placed in a suitable oven. The oven is of the type that may be utilized with a controlled atmosphere, such as non-oxidizing nitrogen or inert gas. Although this process will be described in conjunction with a batch type oven, it is readily apparent that a continuous heat-treating oven, wherein the tobacco moves through a series of chambers during which the process is carried out, may also be employed.

Once the tobacco is placed in the oven the non-oxidizing atmosphere is established therewithin in order to deter combustion of the tobacco in the process, which will be described hereinafter. After the non-oxidizing atmosphere is established within the oven, heat is introduced until the temperature within the oven is above the temperature at which polonium 210 is vaporized, i.e. 500 C.

At 500 C. the polonium 210 is volatile and is therefore vaporized from the tobacco, but, due to the fact that a non-oxidizing atmosphere is present in the oven, there will be no combustion of the tobacco itself. In fact, since tobacco burns at approximately 800 C. in air, there should be little or no effect on the tobacco itself.

Once the polonium 210 is in the vapor state, it is-removed from the oven, as by a conventional exhaust fan, while the tobacco is maintained above the 500 C. temperature level. If the vaporized polonium 2 10 were not removed it would condense on the tobacco as the tobacco was later cooled. With the polonium contaminated atmosphere removed from the oven, the temperature is reduced Within the oven and the tobacco is cooled so that it may be removed from the oven without the outside atmosphere having any undue effect upon the properties of the tobacco.

It is readily apparent that this heating operation will also completely dry the tobacco. It is therefore necessary to moisten the tobacco so that it may be used in the manufacture of smoking products. Many techniques for moistening tobacco are known by those skilled in the art and many of these moistening techniques may be utilized for the treated tobacco.

In a modified form of the invention, the tobacco, preferably in a slitted or shredded form, is placed into a vacuum oven. Thereafter the atmosphere within the oven is exhausted through the use of suitable vacuum pumps until the pressure within the oven is reduced to a low level. Although the degree of the desired vacuum is quite great, it is preferable that the pressure within the vacuum oven be maintained below 2 mm. of mercury.

Once the air has been substantially evacuated from the oven, the temperature is raised in the oven, by suitable means, until it reaches 500 C. thus vaporizing and separating polonium 210 from the tobacco. It is preferred that the vaporized polonium be removed from the interior of the vacuum oven prior to cooling the tobacco and reintroducing an atmosphere into the oven. It is readily apparent that no combustion of the tobacco will occur during the heating process, since an insignificant amount of oxygen, if any, is present Within the oven.

Once the polonium 210 has been exhausted from the oven, the temperature is lowered so as to cool the tobacco therein. Once the tobacco has been cooled sufficiently to prevent its deterioration upon exposure to air, the oven may be opened or a suitable atmosphere may be restored to the oven chamber.

The tobacco may then be removed from the oven and moisture treated as hereinbefore mentioned, in order to prepare it for use as a smoking product.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and that changes may be made in the steps of the methods described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

We claim:

1. A method of treating tobacco to remove undesirable ingredients therefrom, comprising the steps of:

placing a quantity of tobacco in an oven;

establishing a non-oxidizing condition within said oven;

heating said tobacco in said non-oxidizing condition within said oven to a temperature above 500 C., but below the combustion temperature of said tobacco in said non-oxidizing condition, thereby vaporizing and separating said undesirable ingredients from said tobacco;

and then cooling and removing said tobacco from said oven.

2. The method of claim 1 including the additional step of shredding said tobacco before placing said quantity of tobacco in said oven.

3. The method of claim 1 wherein said non-oxidizing condition is an inert gas atmosphere.

4. The method of claim 1 wherein said non-oxidizing condition is substantially a vacuum.

5. The method of claim 1 wherein said harmful ingredient is polonium.

6..A method of treating tobacco to remove undesirable ingredients'therefrom, comprising the steps of:

placing a quantity of tobacco in an oven;

establishing a non-oxidizing atmosphere within said oven;

heating said tobacco surrounded by said non-oxidizing atmosphere within said oven to a temperature above 500 C., but below the combustion temperature of said tobacco in said atmosphere, thereby vaporizing and separating said undesirable ingredients from said tobacco; exhausting said atmosphere from within said oven; and then cooling and removing said tobacco from said oven. 7. A method of treating tobacco toremove undesirable ingredients therefrom, comprising the steps of:

placing a quantity of tobacco ina vacuum oven; exhausting substantially all the atmosphere from said oven, thereby inducing substantially a vacuum within said oven; heating said tobacco within said vacuumized oven to a temperature above 500 (3., but below the combustion temperature of said tobacco in said vacuum, thereby vaporizing and separating said undesirable ingredients from said tobacco; removing said vaporized ingredients from said heated oven; and then cooling and removing said tobacco from said oven. 8. A method as defined in claim 7 wherein the range of temperatures in said heating step is between 500* C. and 800 C.

References Cited UNITED STATES PATENTS 1,201,831 10/1916 Kraus 131143 1,843,638 2/1932 Wenusch 131143 X 2,739,600 3/1956 Staib 131-142 SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner. 

1. A METHOD OF TREATING TOBACCO TO REMOVE UNDERSIRABLE INGREDIENTS THEREFROM, COMPRISING THE STEPS OF: PLACING A QUANTITY OF TOBACCO IN AN OVEN; ESTABLISHING A NON-OXIDIZING CONDITION WITHIN SAID OVEN; HEATING SAID TOBACCO IN SAID NON-OXIDIZING CONDITION WITHIN SAID JOVEN TO A TEMPERATURE ABOUT 500*C., BUT BELOW THE COMBUSTION TEMPERATURE OF SAID TOBACCO IN SAID NON-OXIDIZING CONDITION, THEREBY VAPORIZING AND SEPARATING SAID UNDESIRABLE INGREDIENTS FROM SAID TOBACCO; AND THEN COOLING AND REMOVING SAID TOBACCO FROM SAID OVEN. 